Multiply with 0 at the end of the factor: when writing vertically, align the numbers before 0 and multiply only the numbers before 0; There are several zeros at the end of the * * * of two factors, and several zeros are added at the end of the product.
The change law of product: one factor remains unchanged, another factor expands (or shrinks) several times, and the product expands (or shrinks) by the same multiple. For example, 1: It is known that: axb=2 15, then how much is axbx2=, that is, expand B twice, and the product will also be expanded twice. That is, 2 15x2=430, so axbx2=(430).
For example, 2: known: 2xaxb = 200, then how much axb=, which reduces A by 2 times and the product by 2 times. That is, 200÷2= 100, so axb=( 100). One factor is expanded or reduced by several times, and the other factor is reduced or expanded by the same multiple, and the product remains unchanged.
For example, it is known that axb=5 10. If A is enlarged by 5 times and B is reduced by 5 times, the product is (5 10). If one factor is expanded m times and the other factor is expanded n times, the product is expanded mxn times. If one factor decreases by m times and the other factor decreases by n times, the product decreases by mxn times.
Introduction to mathematics:
Mathematics is a subject that studies concepts such as quantity, structure, change, space and information. Mathematics is a universal means for human beings to strictly describe the abstract structure and mode of things, and can be applied to any problem in the real world. All mathematical objects are artificially defined in essence.
In this sense, mathematics belongs to formal science, not natural science. Different mathematicians and philosophers have a series of views on the exact scope and definition of mathematics. Mathematics plays an irreplaceable role in the development of human history and social life, and it is also an indispensable basic tool for studying and studying modern science and technology.
The knowledge and application of basic mathematics is an indispensable part of individual and group life. The refinement of its basic concepts can be found in ancient mathematical documents of ancient Egypt, Mesopotamia and ancient India. Since then, its development has continued to make small progress. But algebra and geometry at that time were still independent for a long time.
Algebra can be said to be the most widely accepted "mathematics". It can be said that the first mathematics he came into contact with was algebra since everyone began to learn to count when he was a child. Mathematics is a subject that studies numbers, and algebra is also one of the most important parts of mathematics. Geometry is the earliest branch of mathematics studied by people.